Mixing syringe

ABSTRACT

A syringe for mixing and dispensing compounds or mixtures such as dental impression materials. Components of the material to be mixed are placed in a disposable cup which is attached to the syringe. A plunger knob on the syringe is next repeatedly depressed against a return spring to drive a rotating slotted mixing plate back and forth through the material to effect mixing. A pair of handles on the syringe are then squeezed toward each other to force the mixed material out of a nozzle on the cup.

Z ,1 M3 w A MW m t n e t a P S e t a m Ma n um "S m UP MIXING SYRINGE3,618,216 11/1971 Jaeger......................................32/6OInventors: Leonard A. Preston, Monrovia;

Primary Examiner-Robert Peshock Seymour shriverGlendol-a bothAttorney-Russell R Palmer Jr et al of Calif.

Unitek Calif.

[57] ABSTRACT A syringe for mixing and dispensing compounds or mixturessuch as dental impression materials. Components of the material to bemixed are placed in a [73] Assignee: Corporation, Monrovia,

[22] Filed: Nov. 26, 1971 [21] Appl. No.: 202,089

disposable cup which is attached to the syringe. A plunger knob on thesyringe is next repeatedly depressed against a return spring to drive arotating slotted mixing plate back and forth through the 04 MN 25 .6 l"6 M C Sh Him 1] 21 55 material to effect mixing. A pair of handles onthe syr- [58] Field of Search..........32/60, 40 A; 222/412, 413

inge are then squeezed toward each other to force the mixed material outof a nozzle on the cup.

[56] References Cited 12 Claims, 5 Drawing Figures UNITED STATES PATENTS3,552,023 1/1971 Osbeck.....................................32/60 SHEET1 OF 2 PATENTEDAPR 3 I973 Qli PAIENTEDAPR 3 m3 SHEET 2 [1F 2 MIXINGSYRINGE BACKGROUND OF THE INVENTION Multicomponent impression materialshave long been used in dentistry to make an impression or mold of atooth undergoing restorative treatment. A number of elastomers have beendeveloped for this purpose, and are usually formed from a base materialand a catalyst or accelerator. These components are combined just beforethe impression is taken, and the resulting material is applied to thetooth being restored either directly or in an impression tray whichpermits the dentist to obtain a mold of part or all of a dental arch.The impression material quickly sets to form a mold in which a model ofthe tooth or teeth can be cast.

It is important that the impression-material components be mixed quicklyand very thoroughly to insure a dimensionally stable molding materialwith predictable and repeatable characteristics in each batch.Conventional mixing procedure involves manual blending of the componentsin a cup or on a plate, the mixed batch then being transferred to asyringe for injection around a tooth. This procedure does not provideconsistent mixing, and is a messy operation requiring cleanup andusually involving some loss of material during transfer to the syringe.The procedure is also slow, and the impression material may take apremature partial set before being applied to the tooth, leadin g to aninaccurate mold.

Some of these problems are alleviated by recently introduced syringeswhich permit mixing and dispensing in a single container. The materialcomponents are placed in the container which is attached to the syringe,and a plate or vane is reciprocated through the components to mix themtogether. These syringes, however, do not provide thorough consistentmixing which is essential to the preparation of batches of impressionmaterials having consistent properties from batch to batch.

The mixing syringe of this invention includes a dasher or mixing platewhich provides uniform blending of the material components. The mixingplate is coupled through a rotation-inducing mechanism to a plungershaft which is reciprocated by the user. Simple linear motion of theshaft drives the mixing plate back and forth through the materialcomponents, while simultaneously automatically rotating the platethrough a repeatable path for each stroke of the shaft. This combinedlinear and rotary motion of the plate has been found to provide superiormixing of the material components, and consistent properties of thefinal material are easily achieved from batch to batch.

SUMMARY OF THE INVENTION The syringe of this invention includes a hollowhousing adapted to engage and hold a cup containing components of amaterial to be mixed and dispensed. A hollow piston is slidably mountedin the housing, and a shaft is slidably mounted on and extends from anouter end of the piston. A mixing member, which is preferably anapertured disk, is supported adjacent an inner end of the piston by amounting means which is slidably mounted on the piston in contact withthe shaft. Linear movement of the shaft into the piston drives themixing plate from a retracted position (against the inner end of thepiston) into the mixing cup and through the material components.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation of a syringeaccording to the invention;

FIG. 2 is a view on line 22 of FIG. 1;

FIG. 3 is a view on line 3-3 of FIG. 1;

FIG. 4 is a sectional elevation of a portion of a housing used in thesyringe; and

FIG. 5 is a view of the syringe showing the placement of componentsafter mixed material has been expelled from the syringe through anozzle.

DESCRIPTION OF THE PREFERRED EMBODIMENT A syringe according to theinvention is shown in FIG. 1, and includes a hollow cylindrical housing11 having a pair of gripping handles 12 extending therefrom. A forwardend 13 of the housing is enlarged in diameter, and defines threeinwardly extending flanges 14 which form a segmented channel 15 (FIGS. 2and 4). Inner surfaces 16 of flanges 14 are tapered or cam shaped, andsegmented channel 15 is in effect a segmented thread or locking channel.Housing 1 1 has a smooth cylindrical inner bore 17 which tapersoutwardly at its forward end to form a shoulder 18.

A material-receiving cup 20 is generally cylindrical, and tapersinwardly at a forward end to define a forwardly extending tube 21 havingan outlet passage 22 therethrough. A closure cap 23 makes a press fitover tube 21, and has a plug 24 extending into outlet passage 22 toclose the forward end of the cup.

The rear end of cup 20 includes three integrally formed radiallyextending segments or flanges 26 (FIG. 2) which are spaced to fitbetween flanges 14 on housing 11. The cup is mounted on housing 11 bypositioning flanges 14 and 26 as shown in FIG. 2, and then rotating thecup to jam flanges 26 in channel 15 against earn-shaped inner surfaces16 of flanges 14.

A cylindrical ejector piston 30 makes a slip fit within bore 17 ofhousing 1 1. Piston 30 tapers outwardly at its forward or inner end todefine a shoulder 31 which abuts shoulder 18 of the housing to limitrearward travel of the piston. The ejector piston is hollow, and a hub32 having a pair of gripping handles 33 extending therefrom is cementedor otherwise rigidly secured within a rear or outer end of the piston. Aportion of the inner surface of the piston defines a multiple-leadfemale helical thread 34. In a preferred form, three such threads areprovided to form a multiple-lead thread with a linear pitch of 0.333inch and a lead of one inch.

A circular mixing member or plate 38 (FIGS. 1 and 2) makes a loose fitwithin cup 20, and the plate has three annulus-segment apertures oropenings 39 therethrough. An elongate hollow tube 40 extends slightlythrough a central opening in the mixing plate, and is brazed orotherwise rigidly secured to the plate to provide a mounting means forthe plate. Tube extends rearwardly into hollow piston 30, and makes aslip fit through an inwardly extending shoulder 41 integrally formedwithin the piston. Tube 40 terminates at a rear or outer end 43 withinthe piston and positioned adjacent the beginning of multiple-lead thread34.

A rotary means such as a rotor or follower member 45 (FIGS. 1 and 3) isrigidly secured around end 43 of tube 40, and has three male threads 46extending radially therefrom to form a male multiple-lead thread matingwith female thread 34 in the piston. The follower member is cemented orotherwise rigidly secured to the periphery of tube 40, and end 43 of thetube is also flared or swedged against the follower member (FIG. 1) tohold the components together.

A compression coil spring 47 (FIG. 1) is positione around tube 40 withinpiston 30, and the forward end of the spring bears on a rear face ofshoulder 41. The opposite end of the spring bears against a pair ofwashers 48 which are seated on follower member 45. A resilient seal 50is seated in a recess 51 at the forward end of piston 30, and the sealbears against the periphery of tube 40.

An elongate cylindrical shaft 55 makes a slip fit within tube 40 andseats against a ball 56 ata closed forward end 57 of the tube. Shaft 55extends rearwardly to make a slip fit through a central opening 59 inhub 32. A knob 60 is rigidly secured at a rear or outer end of shaft 55.A C-ring retainer 61 is fitted on shaft 55 to limit rearward motion ofthe shaft to the position shown in FIG. 1.

Housing 1 1, cap 23, hub 32, follower member 45 and knob 60 arepreferably molded from a plastic material such as nylon. Cup 20 ispreferably molded from polyethylene. plastic, and seal 50 is formed frompolytetrafluoroethylene plastic (sold under the trademark Teflon).Mixing plate 38, tube 40 and shaft 55 are preferably made of stainlesssteel.

In operation, the components of a material to be mixed and dispensed arefirst loaded into cup 20. The cup preferably includes graduations orlines 62 (FIG. 5) to guide the user in the amount of material to beloaded. The cup is then secured to housing 11 as described above, andplug 24 is checked to insure that it is securely in place. i

The user then grips the syringe by handles 33, and

depresses knob 60 to drive shaft 55 forwardly toward the front of thecup. This motion forces mixing plate 38 forwardly through the cup andthe materials contained therein, as the shaft bears directly on ball 56at the end of tube 40, and the tube in turn is rigidly secured to themixing plate. As the mixing plate and tube are driven forwardly by theshaft, follower member 45 is carried along with the tube and is forcedto rotate as threads 46 follow threads 34. As the follower member isrigidly secured to the tube, this rotary motion is transmitted throughthe tube to the mixing plate. The rotary motion, however, is isolatedfrom shaft 55 because tube 40 rotates freely around the shaft. Knob 60thus remains stationary under the users thumb during a mixing operation,and does not tend to rotate with the internal parts of the syringe.

When the mixing plate is driven forwardly through a full stroke to thebottom or forward end of cup 20, pressure on knob 60 is relaxed and themoving parts of the syringe are returned to the original retractedposition (shown in FIG. 1) by return spring 47. Pressure is then againapplied to knob 60 to cycle the mixing plate back and forth repeatedlythrough the materials in the cup. These materials are extruded throughopenings 39 in the mixing plate, and thin materials may also flow aroundthe periphery of the mixing plate as it reciprocates within the cup.

The combined linear and rotary motion of the mixing plate has been foundto produce a rapid and thorough stirring or mixing action of the severalcomponents of the material being handled. The rotary motion is producedautomatically as the knob is moved linearly, and the knob does not twistunder the users thumb. The segmented-annulus shape of openings 39 in themixing plate have been found to produce particularly efficient mixing ofcomponents used to prepare dental impression materials.

Seal 50 prevents any of the materials being mixed from flowing into theinterior of ejector piston 30 during the rearward or return stroke ofthe mixing plate. As best seen in FIG. 1, the front surface of this sealis recessed slightly below the forward end of the ejector piston toprevent the mixing plate from bearing directly against the seal andextruding material therethrough.

After the material has been thoroughly mixed by an appropriate number ofstrokes of the mixing plate, closure cap 23 is removed from the end ofcup 20 and the mixed material is ready to be dispensed. If desired, anaccessory nozzle 64 as shown in FIG. 5 can be fitted over tube 21 of thecup to guide the mixed material to a specific location. This nozzle isparticularly useful when dental impression material is being mixed, andthe material is to be dispensed around a tooth undergoing restorativetreatment.

Dispensing of the material is accomplished by squeezing handles 12 and33 toward each other to force ejector piston 30 forwardly in cup 20.During this operation, mixing plate 38 is in the rearward or fullyretracted position as shown in FIG. 1. The mixing plate and piston thusmove forward in the cup as a unit, forcing the mixed material throughoutlet passage 22 into nozzle 64. When the mixing plate bottoms at theforward end of the cup, the operating handles are in the position shownin FIG. 5, and all of the mixed material has been dispensed from thecup.

Although cup 20 may be reused repeatedly, it will often be convenient todispose of the cup after each use to eliminate cleaning. One of thecomponents of a multi-component material may also be packaged in thecup, and the other component added thereto immediately prior to mixing.The cup is inexpensively molded from plastic, can be treated as adisposable throwaway item.

There'has been described a mixing and dispensing syringe which isparticularly suitable for handling multi-component dental impressionmaterials. The syringe is fast and easy to use, and produces thoroughmixing of the material components. When mixing is complete, dispensingof the material is readily accomplished simply by shifting the positionof the hands on the syringe to urge the operating handles together.

What is claimed is:

l. A syringe for mixing and dispensing a material formed from severalcomponents which are mixed together before the material is used,comprising:

a hollow housing adapted to engage and hold a cup containing thematerial components;

a hollow piston slidably mounted within the housing;

a shaft slidably mounted in and extending from a first end of thepiston;

a mixing member; and

a mounting means secured to the mixing member and slidably mounted inthe piston in contact with the shaft whereby linear movement of theshaft into the piston drives the mixing plate from a retracted positionagainst a second end of the piston into the mixing cup and through thematerial components, the mounting means including rotary means coupledto the piston and operative to rotate the mixing member when the shaftis moved linearly,

the piston and retracted mixing plate being movable as a unit withrespect to the housing to force the material through the cup aftermixing is complete.

2. The syringe defined in claim 1 in which the mounting means isrotationally free with respect to the shaft whereby rotation of themixing plate does not cause shaft rotation as the shaft is movedlinearly.

3. The syringe defined in claim 2 and further comprising a return springdisposed between the piston and mounting means to urge the mixing memberinto a retracted position.

4. The syringe defined in claim 3 in which the mixing member is aslotted disk, and in which the rotary means and piston include matedhelically threaded portions for rotating the disk.

5. A syringe for mixing and dispensing compositions such as a dentalimpression material prepared from several components which are blendedjust before the material is to be used, comprising:

a cup for holding the material components and having an open end and acapped end with a releasable closure;

a hollow housing releasably engaged with the cup over the open endthereof;

a piston slidably fitted in and extending out of the housing away fromthe cup, the piston having an inner end extending into the cup when thepiston is moved toward the capped end;

a mixing plate disposed between the inner end of the piston and thecapped end of the cup;

a mounting means secured to the mixing plate and movably mounted on thepiston so linear movement of the mounting means moves the mixing platefrom a retracted position against the inner end of the piston to anextended position adjacent the capped end of the cup, the mounting meansincluding rotary means coupled to the piston and operative to causerotation of the mixing plate as it is moved between the retracted andextended position; and

a shaft slidably mounted on the piston in contact with the mountingmeans, and extending from an outer end of the piston to be linearlymovable to drive the mounting means and mixing plate, the shaft andmounting means being rotationally free with respect to each otherwhereby mixing-plate rotation induced by the rotary means is isolatedfrom the linearly movable shaft. 6. The syringe defined in claim 5 andfurther comprising a return spring disposed between the piston andmounting means, and operative to urge the mixing plate toward theretracted position.

7. The syringe defined in claim 6 in which the housing and piston eachhave handles extending therefrom, the mixing plate is a disk with aplurality of apertures therethrough, the mounting means includes a tuberigidly secured to the mixing-plate disk and slidably mounted on thepiston, the shaft being received in the tube in linear drivingrelationship, and the rotary means comprises a threaded follower rigidlysecured to the tube, the piston having a threaded portion receiving thefollower whereby the follower, tube and disk are rotated as the tube islinearly driven by the shaft.

8. The syringe defined in claim 5 in which the housing and piston eachhave handles extending therefrom, and the shaft includes a knob at itsouter end, whereby mixing is performed by gripping the syringe toreciprocate the knob with respect to the piston handle, and dispensingof the mixed material is performed by removing the cup closure anddrawing the housing and piston handles together to drive the piston andretracted mixing plate into the cup to expel material therefrom.

9. The syringe defined in claim 5 in which the mounting means includes ahollow tube having a closed end rigidly secured to the mixing plate, thepiston defining a bore in which the tube is slidably fitted, and a balldisposed in the tube at the closed end, the shaft being fitted withinthe tube to bear against the ball, and further comprising a returnspring disposed between the piston and mounting means to urge the mixingplate toward the retracted position.

10. The syringe defined in claim 9 in which the rotary means comprises afollower having external threads and being rigidly secured to the tube,the piston bore defining mating threads receiving the follower threads.

1 1. The syringe defined in claim 10 and further comprising a sealdisposed around the tube and seated at the inner end of the piston.

12. The syringe defined in claim 5 in which the cup is generallycylindrical and the mixing plate is a circular disk having a diameterslightly smaller than an inside diameter of the cup, the disk includinga plurality of apertures therethrough.

1. A syringe for mixing and dispensing a material formed from severalcomponents which are mixed together before the material is used,comprising: a hollow housing adapted to engage and hold a cup containingthe material components; a hollow piston slidably mounted within thehousing; a shaft slidably mounted in and extending from a first end ofthe piston; a mixing member; and a mounting means secured to the mixingmember and slidably mounted in the piston in contact with the shaftwhereby linear movement of the shaft into the piston drives the mixingplate from a retracted position against a second end of the piston intothe mixing cup and through the material components, the mounting meansincluding rotary means coupled to the piston and operative to rotate themixing member when the shaft is moved linearly, the piston and retractedmixing plate being movable as a unit with respect to the housing toforce the material through the cup after mixing is complete.
 2. Thesyringe defined in claim 1 in which the mounting means is rotationallyfree with respect to the shaft whereby rotation of the mixing plate doesnot cause shaft rotation as the shaft is moved linearly.
 3. The syringedefined in claim 2 and further comprising a return spring disposedbetween the piston and mounting means to urge the mixing member into aretracted position.
 4. The syringe defined in claim 3 in which themixing member is a slotted disk, and in which the rotary means andpiston include mated helically threaded portions for rotating the disk.5. A syringe for mixing and dispensing compositions such as a dentalimpression material prepared from several components which are blendedjust before the material is to be used, comprising: a cup for holdingthe material components and having an open end and a capped end with areleasable closure; a hollow housing releasably engaged with the cupover the open end thereof; a piston slidably fitted in and extending outof the housing aWay from the cup, the piston having an inner endextending into the cup when the piston is moved toward the capped end; amixing plate disposed between the inner end of the piston and the cappedend of the cup; a mounting means secured to the mixing plate and movablymounted on the piston so linear movement of the mounting means moves themixing plate from a retracted position against the inner end of thepiston to an extended position adjacent the capped end of the cup, themounting means including rotary means coupled to the piston andoperative to cause rotation of the mixing plate as it is moved betweenthe retracted and extended position; and a shaft slidably mounted on thepiston in contact with the mounting means, and extending from an outerend of the piston to be linearly movable to drive the mounting means andmixing plate, the shaft and mounting means being rotationally free withrespect to each other whereby mixing-plate rotation induced by therotary means is isolated from the linearly movable shaft.
 6. The syringedefined in claim 5 and further comprising a return spring disposedbetween the piston and mounting means, and operative to urge the mixingplate toward the retracted position.
 7. The syringe defined in claim 6in which the housing and piston each have handles extending therefrom,the mixing plate is a disk with a plurality of apertures therethrough,the mounting means includes a tube rigidly secured to the mixing-platedisk and slidably mounted on the piston, the shaft being received in thetube in linear driving relationship, and the rotary means comprises athreaded follower rigidly secured to the tube, the piston having athreaded portion receiving the follower whereby the follower, tube anddisk are rotated as the tube is linearly driven by the shaft.
 8. Thesyringe defined in claim 5 in which the housing and piston each havehandles extending therefrom, and the shaft includes a knob at its outerend, whereby mixing is performed by gripping the syringe to reciprocatethe knob with respect to the piston handle, and dispensing of the mixedmaterial is performed by removing the cup closure and drawing thehousing and piston handles together to drive the piston and retractedmixing plate into the cup to expel material therefrom.
 9. The syringedefined in claim 5 in which the mounting means includes a hollow tubehaving a closed end rigidly secured to the mixing plate, the pistondefining a bore in which the tube is slidably fitted, and a balldisposed in the tube at the closed end, the shaft being fitted withinthe tube to bear against the ball, and further comprising a returnspring disposed between the piston and mounting means to urge the mixingplate toward the retracted position.
 10. The syringe defined in claim 9in which the rotary means comprises a follower having external threadsand being rigidly secured to the tube, the piston bore defining matingthreads receiving the follower threads.
 11. The syringe defined in claim10 and further comprising a seal disposed around the tube and seated atthe inner end of the piston.
 12. The syringe defined in claim 5 in whichthe cup is generally cylindrical and the mixing plate is a circular diskhaving a diameter slightly smaller than an inside diameter of the cup,the disk including a plurality of apertures therethrough.